Lubricating oil deterioration and nitration is a problem with any lubricating oil when used in an engine. This problem is exacerbated in diesel engines that the system because the level of NOx produced in such engines promotes oil nitration and deterioration.
Elevated temperatures typically found in engines affect lubricating oil deterioration and increase the level of acid contamination. This problem is exacerbated in heavy-duty diesel engines equipped with exhaust gas re-circulation systems because the operating temperatures for these engines are higher than other types of engines. The level of acid contamination is also higher than other types of engines. Higher operating temperatures and acid contamination may result in increased bearing corrosion. Lubricating engines with the lubricating oil of this invention resulted in improved bearing corrosion control in heavy-duty diesel engines.
It has now been discovered that the combination of one or more EC-treated polyalkene succinimides and one or more borated polyalkene succinimides with a specific phenolic antioxidant controls bearing corrosion and controls valve train wear.
Accordingly, the present invention comprises:
A lubricating oil additive composition comprising:
(a) one or more ethylene carbonate-treated succinimides,
(b) one or more borated succinimides, and
(c) one or more phenolic antioxidants selected from those of the formulae: 
wherein each R is an alkyl group of 7 to 9 carbon atoms.
The present invention further provides:
A lubricating oil composition comprising a major amount of an oil of lubricating viscosity and a minor amount of the lubricating oil additive composition comprising:
(a) one or more ethylene carbonate-treated succinimides,
(b) one or more borated succinimides, and
(c) one or more phenolic antioxidants selected from those of the formulae: 
wherein each R is an alkyl group of 7 to 9 carbon atoms.
The present invention additionally provides a method of lubricating an engine comprising operating the engine with the lubricating oil composition of the present invention.
The present invention additionally provides a method for reducing valve train wear in diesel engines comprising lubricating the diesel engine with the lubricating oil composition of the present invention.
The present invention additionally provides method for controlling bearing corrosion in diesel engines comprising lubricating the diesel engine with the lubricating oil composition the present invention.
Among other factors, the present invention is based on the surprising discovery that the unique combination of one or more EC-treated polyalkene succinimides and one or more borated polyalkene succinimides with a specific phenolic antioxidant provides decreased bearing corrosion and decrease valve train wear.